Gene Summary

Gene:DLK1; delta like non-canonical Notch ligand 1
Aliases: DLK, FA1, ZOG, pG2, DLK-1, PREF1, Delta1, Pref-1
Summary:This gene encodes a transmembrane protein that contains multiple epidermal growth factor repeats that functions as a regulator of cell growth. The encoded protein is involved in the differentiation of several cell types including adipocytes. This gene is located in a region of chromosome 14 frequently showing unparental disomy, and is imprinted and expressed from the paternal allele. A single nucleotide variant in this gene is associated with child and adolescent obesity and shows polar overdominance, where heterozygotes carrying an active paternal allele express the phenotype, while mutant homozygotes are normal. [provided by RefSeq, Nov 2015]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein delta homolog 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
Show (9)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • MicroRNAs
  • Epigenetics
  • Thoracic Neoplasms
  • Intercellular Signaling Peptides and Proteins
  • Epithelial-Mesenchymal Transition
  • Tumor Microenvironment
  • Tissue Distribution
  • Cell Differentiation
  • Neoplastic Cell Transformation
  • Hepatocellular Carcinoma
  • Homeodomain Proteins
  • Stomach Cancer
  • Rhabdomyosarcoma, Embryonal
  • Iodide Peroxidase
  • Childhood Cancer
  • RNA, Untranslated
  • alpha-Fetoproteins
  • Pituitary Tumors
  • Lung Cancer
  • DNA Methylation
  • Down-Regulation
  • Cancer Stem Cells
  • Genomic Imprinting
  • Biomarkers, Tumor
  • Gene Expression Profiling
  • Cancer Gene Expression Regulation
  • RNA Interference
  • Risk Factors
  • Membrane Proteins
  • Cell Proliferation
  • Multigene Family
  • Tumor Burden
  • Chromosome 14
  • Oligonucleotide Array Sequence Analysis
  • Molecular Sequence Data
  • Proteins
  • Multiple Myeloma
  • Liver Cancer
  • Survival Rate
  • Long Noncoding RNA
  • Neuroblastoma
Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (7)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: DLK1 (cancer-related)

Huang CC, Cheng SH, Wu CH, et al.
Delta-like 1 homologue promotes tumorigenesis and epithelial-mesenchymal transition of ovarian high-grade serous carcinoma through activation of Notch signaling.
Oncogene. 2019; 38(17):3201-3215 [PubMed] Related Publications
Ovarian carcinoma is the most lethal type of gynecologic malignancies. Alterations of Notch pathway are prevalent in ovarian carcinogenesis. This study investigated the expression profile and function of delta-like 1 homolog (DLK1), a non-canonical Notch ligand, during ovarian carcinogenesis. Tissue microarray (TMA) consisting of surgically resected samples from 221 patients with ovarian carcinoma was constructed for DLK1 expression. DLK1 overexpression or knockdown was achieved by adenovirus gene delivery to evaluate the effect of DLK1 on the oncogenic behaviors in ovarian cancer cells and in xenografted tumors. TMA analysis revealed that elevated DLK1 expression was correlated with stages, lymph node metastasis and E-cadherin downregulation. Despite no influence on survival among ovarian carcinoma patients, DLK1 overexpression was specially associated with overall survival and progression free survival in high-grade serous carcinoma (HGSC) patients, constituting an independent prognostic factor for these patients. By adenovirus gene delivery, it was found modulation of cellular DLK1 level regulated the tumorigenic behaviors and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Immunohistochemical analysis further showed that DLK1 overexpression resulted in escalated proliferation, angiogenesis, EMT and Notch activities. Application of recombinant DLK1 extracellular domain (rDLK1-EC) recapitulated the tumorigenic behaviors of DLK1 in ovarian cancer cells. By using neutralizing antibody or pharmaceutical inhibitor, blockade of Notch signaling attenuated the tumorigenic behaviors evoked by DLK1 overexpression. The present study indicates that DLK1 overexpression participates in ovarian carcinogenesis through Notch activation and EMT induction. Moreover, DLK1 may constitute a novel diagnostic biomarker and therapeutic target for HGSC.

Valdmanis PN, Kim HK, Chu K, et al.
miR-122 removal in the liver activates imprinted microRNAs and enables more effective microRNA-mediated gene repression.
Nat Commun. 2018; 9(1):5321 [PubMed] Free Access to Full Article Related Publications
miR-122 is a highly expressed liver microRNA that is activated perinatally and aids in regulating cholesterol metabolism and promoting terminal differentiation of hepatocytes. Disrupting expression of miR-122 can re-activate embryo-expressed adult-silenced genes, ultimately leading to the development of hepatocellular carcinoma (HCC). Here we interrogate the liver transcriptome at various time points after genomic excision of miR-122 to determine the cellular consequences leading to oncogenesis. Loss of miR-122 leads to specific and progressive increases in expression of imprinted clusters of microRNAs and mRNA transcripts at the Igf2 and Dlk1-Dio3 loci that could be curbed by re-introduction of exogenous miR-122. mRNA targets of other abundant hepatic microRNAs are functionally repressed leading to widespread hepatic transcriptional de-regulation. Together, this reveals a transcriptomic framework for the hepatic response to loss of miR-122 and the outcome on other microRNAs and their cognate gene targets.

Kumar S, Srivastav RK, Wilkes DW, et al.
Estrogen-dependent DLL1-mediated Notch signaling promotes luminal breast cancer.
Oncogene. 2019; 38(12):2092-2107 [PubMed] Related Publications
Aberrant Notch signaling is implicated in several cancers, including breast cancer. However, the mechanistic details of the specific receptors and function of ligand-mediated Notch signaling that promote breast cancer remains elusive. In our studies we show that DLL1, a Notch signaling ligand, is significantly overexpressed in ERα

Zhang RM, Tang T, Yu HM, Yao XD
LncRNA DLX6-AS1/miR-129-5p/DLK1 axis aggravates stemness of osteosarcoma through Wnt signaling.
Biochem Biophys Res Commun. 2018; 507(1-4):260-266 [PubMed] Related Publications
Osteosarcoma is the most common primary bone tumor and occurs most frequently in adolescents. Cancer stem cells (CSCs) are resistant to chemotherapy and radiotherapy, and can drive cancer recurrence. In this study, we aimed to investigate the effect of Long noncoding RNAs (lncRNAs) DLX6-AS1 on osteosarcoma stemness and the underlying mechanism involved. DLX6-AS1 enhanced osteosarcoma stemness in vitro and in vivo. Moreover, DLX6-AS1 competitively interacted with miR-129-5p to DLK1, resulting in activation of Wnt signaling and promotion of stemness in osteosarcoma. DLX6-AS1 functionally interplayed with miR-129-5p to form a reciprocal feedback loop to activate Wnt signaling. High DLX6-AS1 expression was observed in osteosarcoma tissues, and predicted a poor prognosis for osteosarcoma patients. Our study suggests that DLX6-AS1, combined with miR-129-5p and DLK1, can be utilized as factors for the clinical diagnosis and prognosis of osteosarcoma, and may be potential targets for the treatment of osteosarcoma.

Bruno C, Blagoskonov O, Barberet J, et al.
Sperm imprinting integrity in seminoma patients?
Clin Epigenetics. 2018; 10(1):125 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Testicular germ cell tumor such as seminoma is strongly associated with male reproductive problems commonly associated with the alteration of sperm parameters as described in testicular dysgenesis syndrome. Interestingly, numerous studies have reported that the precursor of germ cell cancer, germ cell neoplasia in situ (GCNIS), present similarities to fetal gonocytes, specifically characterized by global DNA hypomethylation particularly on imprinting sequences. These disorders may have a common origin derived from perturbations of embryonal programming during fetal development. Presently, there is no available information concerning the sperm DNA methylation patterns of testicular cancer patients. For the first time, we evaluated the sperm imprinting of seminoma patients. A total of 92 cryopreserved sperm samples were included, 31 before seminoma treatment (S): 23 normozoospermic (SN) and 8 oligozoospermic (SO) and 61 sperm controls samples: 31 normozoospermic (N) and 30 oligozoospermic (O). DNA methylation levels of seven differentially methylated regions (DMRs) of imprinted genes [H19/IGF2: IG-DMR (CTCF3 and CTCF6 of H19 gene); IGF2-DMRs (DMR0 and DMR2); MEG3/DLK1:IG-DMR; SNURF:TSS-DMR; KCNQ1OT1:TSS-DMR] were assessed by pyrosequencing. All comparative analyses were adjusted for age.
RESULTS: Comparisons of sperm DNA methylation levels between seminoma (S) and normozoospermic (N) samples showed a significant difference for the SNURF sequence (p = 0.017), but after taking into account the sperm parameters, no difference was observed. However, we confirmed a significant association between oligozoospermia (O) and imprinting defects for H19/IGF2-CTCF6 (p = 0.001), MEG3/DLK1 (p = 0.017), IGF2-DMR2 (p = 0.022), and SNURF (p = 0.032) in comparison with control groups (N).
CONCLUSIONS: This study highlights the high risk of sperm imprinting defects in cases of oligozoospermia and shows for the first time that seminoma patients with normal spermatogenesis present sperm imprinting integrity. These data suggest a low probability of the involvement of a common imprinting defect in fetal cells leading to both TGCT and subfertility.

Terashima M, Ishimura A, Wanna-Udom S, Suzuki T
J Biol Chem. 2018; 293(47):18016-18030 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Long noncoding RNAs (lncRNAs) are important regulatory molecules in various biological and pathological processes, including cancer development. We have previously shown that the

Sellers ZP, Schneider G, Maj M, Ratajczak MZ
Analysis of the Paternally-Imprinted DLK1-MEG3 and IGF2-H19 Tandem Gene Loci in NT2 Embryonal Carcinoma Cells Identifies DLK1 as a Potential Therapeutic Target.
Stem Cell Rev Rep. 2018; 14(6):823-836 [PubMed] Related Publications
The paternally-imprinted genes insulin-like growth factor 2 (IGF2), H19, delta-like homologue 1 (DLK1), and maternally-expressed gene 3 (MEG3) are expressed from the tandem gene loci IGF2-H19 and DLK1-MEG3, which play crucial roles in initiating embryogenesis and development. The erasure of imprinting (EOI) at differentially methylated regions (DMRs) which regulate the expression of these genes maintains the developmental quiescence of primordial germ cells (PGCs) migrating through the embryo proper during embryogenesis and prevents them from forming teratomas. To address the potential involvement of the IGF2-H19 and DLK1-MEG3 loci in the pathogenesis of embryonal carcinoma (EC), we investigated their genomic imprinting at DMRs in the human PGC-derived EC cell line NTera-2 (NT2). We observed EOI at the IGF2-H19 locus and, somewhat to our surprise, a loss of imprinting (LOI) at the DLK1-MEG3 locus. As a result, NT2 cells express imprinted gene ratios from these loci such that there are i) low levels of the proliferation-promoting IGF2 relative to ii) high levels of the proliferation-inhibiting long noncoding RNA (lncRNA) H19 and iii) high levels of proliferation-promoting DLK1 relative to iv) low levels of the proliferation-inhibiting lncRNA MEG3. Consistent with this pattern of expression, the knockdown of DLK1 mRNA by shRNA resulted in decreased in vitro cell proliferation and in vivo tumor growth as well as decreased in vivo organ seeding by NT2 cells. Furthermore, treatment of NT2 cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-azaD) inhibited their proliferation. This inhibition was accompanied by changes in expression of both tandem gene sets: a decrease in the expression of DLK1 and upregulation of the proliferation-inhibiting lncRNA MEG3, and at the same time upregulation of IGF2 and downregulation of the lncRNA H19. These results suggest that the DLK1-MEG3 locus, and not the IGF2-H19 locus, drives the tumorigenicity of NT2 cells. Based on these results, we identified DLK1 as a novel treatment target for EC that could be downregulated by 5-azaD.

Xu Y, Qin Q, Chen R, et al.
SIRT1 promotes proliferation, migration, and invasion of breast cancer cell line MCF-7 by upregulating DNA polymerase delta1 (POLD1).
Biochem Biophys Res Commun. 2018; 502(3):351-357 [PubMed] Related Publications
Sirtuin 1 (SIRT1), class III histone deacetylase, plays an important character in cell proliferation, cell cycle, apoptosis, energy metabolism and DNA repair. In recent years, researchers have attached increasing attention on the role of SIRT1 in tumorigenesis, development and drug resistance. The effect of SIRT1 on breast cancer is still controversial and its exact role remains to be elucidated. In the present study, we investigated the significant role of SIRT1 in breast cancer by exploring the effect of SIRT1 on DNA polymerase delta1 (POLD1), the gene coding for DNA polymerase δ catalytic subunit p125. Immunohistochemistry showed that the protein expression level of SIRT1 was higher in breast cancer tissues relative to adjacent normal tissues. Knockdown of SIRT1 by shRNA decreased the proliferation, migration, and invasion of human breast cancer cell line MCF-7, while the overexpression of SIRT1 promoted the proliferation, migration, and invasion of MCF-7 cells. Clinically, the immunohistochemistry results revealed that the expression of SIRT1 was positively correlated with p125. Further analysis demonstrated that silencing of SIRT1 increased the expression of p53, while the expression level of POLD1/p125 decreased, and the result by overexpressing SIRT1 was opposite. Collectively, these data suggest that SIRT1 is an oncogenic factor in breast cancer cells and can be involved in the progression of breast cancer by inhibiting p53 and activating POLD1. Our finding provides new insights into the mechanisms of breast cancer.

Tetzlaff F, Adam MG, Feldner A, et al.
MPDZ promotes DLL4-induced Notch signaling during angiogenesis.
Elife. 2018; 7 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Angiogenesis is coordinated by VEGF and Notch signaling. DLL4-induced Notch signaling inhibits tip cell formation and vessel branching. To ensure proper Notch signaling, receptors and ligands are clustered at adherens junctions. However, little is known about factors that control Notch activity by influencing the cellular localization of Notch ligands. Here, we show that the multiple PDZ domain protein (MPDZ) enhances Notch signaling activity. MPDZ physically interacts with the intracellular carboxyterminus of DLL1 and DLL4 and enables their interaction with the adherens junction protein Nectin-2. Inactivation of the MPDZ gene leads to impaired Notch signaling activity and increased blood vessel sprouting in cellular models and the embryonic mouse hindbrain. Tumor angiogenesis was enhanced upon endothelial-specific inactivation of MPDZ leading to an excessively branched and poorly functional vessel network resulting in tumor hypoxia. As such, we identified MPDZ as a novel modulator of Notch signaling by controlling ligand recruitment to adherens junctions.

Shen CH, Tung SY, Tseng MJ, Leu YW
Inverse Correlation between Methylation and Expression of the Delta-like Ligand 1 Gene in Gastric Cancer.
Chin J Physiol. 2018; 61(2):65-74 [PubMed] Related Publications
Notch signaling is a candidate pathway that transmits environmental information into the cell and interferes with the epigenome of gastric cancer. This study aimed to explore if the Notch pathway was abnormally regulated during gastric tumorigenesis. To achieve the goal, Delta-like ligand 1 (DLL1) gene expression, Notch upstream signal, promoter methylation and its correlation with DLL1 expression were examined by methylation-specific polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in cultured gastric cancer cell lines or gastric cancer patient samples. Immunostainings and tissue arrays (n = 40) were used to confirm the DLL1 expression was down-regulated in cancer cells. Transient or stable Notch1 active domain (NICD)-overexpression suppressed proliferation of the gastric cells but the in vivo tumor growth was enhanced. The results of abnormal DLL1 methylation and expression observed in early gastric lesions and in gastric cancers may be relevant to the pathogenesis of gastric cancer.

Ferreira A, Lamy M, Margarida Rocha M, et al.
Production and characterization of a novel Delta-like 1 functional unit as a tool for Notch pathway activation and generation of a specific antibody.
Protein Expr Purif. 2018; 146:8-16 [PubMed] Related Publications
Notch signalling is an evolutionary conserved cell-to-cell communication pathway crucial for development and tissue homeostasis. Abnormal Notch signalling by mutations or deregulated expression of its receptors and/or ligands can lead to cancer making it a potential therapeutic target. Delta-like1 (DLL1) is a ligand of the Notch pathway implicated in different types of cancer, including breast cancer. Herein, we produced rhDLL1-DE3, a novel soluble form of DLL1 protein, which contains the DSL domain and EGF1-3 repeats critical for Notch pathway activation. cDNA fragments of human DLL1, encoding truncated versions of DLL1 with regions required to activate Notch receptors, were cloned and expressed as histidine-fused proteins in bacterial and mammalian cells. Expression tests in mammalian cells showed almost exclusively expression of the rhDLL1-DE3 protein form comprising the minimal binding regions DSL to EGF3 to Notch receptors. The highest yield of rhDLL1-DE3 was obtained from E. coli inclusion bodies. The produced protein, with purity higher than 95% bound to human Notch1 recombinant protein, by both Biolayer interferometry and ELISA assays. Cellular assays revealed rhDLL1-DE3 was biologically active as it increased expression of Notch-dependent genes in inducible pluripotent and breast cancer cells. Moreover, rhDLL1-DE3 allowed the generation of polyclonal antibodies by immunization that efficiently recognized DLL1 proteins by immunoblot, and caused a significant decrease of Notch1 expression in MCF7 breast cancer cells. The rhDLL1-DE3 protein might thus be used for Notch pathway activation and to generate anti-DLL1 monoclonal antibodies by immunization or phage display technology to unveil the effect of DLL1 in breast cancer.

Zhang H, Zheng J, Shen H, et al.
Curcumin Suppresses In Vitro Proliferation and Invasion of Human Prostate Cancer Stem Cells by Modulating DLK1-DIO3 Imprinted Gene Cluster MicroRNAs.
Genet Test Mol Biomarkers. 2018; 22(1):43-50 [PubMed] Related Publications
AIMS: Curcumin can suppress human prostate cancer (HuPCa) cell proliferation and invasion. However, it is not known whether curcumin can inhibit HuPCa stem cell (HuPCaSC) proliferation and invasion.
MATERIALS AND METHODS: We used methyl thiazolyl tetrazolium and Transwell assays to examine the proliferation and invasion of the HuPCaSC lines DU145 and 22Rv1 following curcumin or dimethyl sulfoxide (control) treatment. The microRNA (miRNA) expression levels in the DLK1-DIO3 imprinted genomic region in the cells and in tumor tissues from patients with PCa were examined using microarray and quantitative PCR.
RESULTS: The median inhibitory concentration of curcumin for HuPCa cells significantly inhibited HuPCaSC proliferation and invasion in vitro. The miR-770-5p and miR-1247 expression levels in the DLK1-DIO3 imprinted gene cluster were significantly different between the curcumin-treated and control HuPCaSCs. Overexpression of these positive miRNAs significantly increased the inhibition rates of miR-770-5p- and miR-1247-transfected HuPCaSCs compared to the control miR-Mut-transfected HuPCaSCs. Lastly, low-tumor grade PCa tissues had higher miR-770-5p and miR-1247 expression levels than high-grade tumor tissues.
CONCLUSIONS: Curcumin can suppress HuPCaSC proliferation and invasion in vitro by modulating specific miRNAs in the DLK1-DIO3 imprinted gene cluster.

Craze ML, Cheung H, Jewa N, et al.
MYC regulation of glutamine-proline regulatory axis is key in luminal B breast cancer.
Br J Cancer. 2018; 118(2):258-265 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
BACKGROUND: Altered cellular metabolism is a hallmark of cancer and some are reliant on glutamine for sustained proliferation and survival. We hypothesise that the glutamine-proline regulatory axis has a key role in breast cancer (BC) in the highly proliferative classes.
METHODS: Glutaminase (GLS), pyrroline-5-carboxylate synthetase (ALDH18A1), and pyrroline-5-carboxylate reductase 1 (PYCR1) were assessed at DNA/mRNA/protein levels in large, well-characterised cohorts.
RESULTS: Gain of PYCR1 copy number and high PYCR1 mRNA was associated with Luminal B tumours. High ALDH18A1 and high GLS protein expression was observed in the oestrogen receptor (ER)+/human epidermal growth factor receptor (HER2)- high proliferation class (Luminal B) compared with ER+/HER2- low proliferation class (Luminal A) (P=0.030 and P=0.022 respectively), however this was not observed with mRNA. Cluster analysis of the glutamine-proline regulatory axis genes revealed significant associations with molecular subtypes of BC and patient outcome independent of standard clinicopathological parameters (P=0.012). High protein expression of the glutamine-proline enzymes were all associated with high MYC protein in Luminal B tumours only (P<0.001).
CONCLUSIONS: We provide comprehensive clinical data indicating that the glutamine-proline regulatory axis plays an important role in the aggressive subclass of luminal BC and is therefore a potential therapeutic target.

Liu W, Liu X, Wang L, et al.
PLCD3, a flotillin2-interacting protein, is involved in proliferation, migration and invasion of nasopharyngeal carcinoma cells.
Oncol Rep. 2018; 39(1):45-52 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Phospholipase C (PLC) is a pivotal enzyme in the phosphoinositide pathway that promotes the second messengers, diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3), to participate in eukaryotic signal transduction. Several PLC isozymes are associated with cancer, such as PLC-β1, PLC-δ1, PLC-ε and PLC-γ1. However, the role of PLC-δ3 (PLCD3) in nasopharyngeal carcinoma (NPC) has not been investigated to date. In our previous study, we demonstrated that flotillin2 (Flot2) plays a pro-neoplastic role in NPC and is involved in tumour progression and metastasis. In the present study, we screened the interacting proteins of Flot2 using the yeast two-hybrid (Y2H) method and verified the interaction between PLCD3 and Flot2 by co-immunoprecipitation. We also investigated the biological functions of PLCD3 in NPC. Inhibition of PLCD3 expression impaired the malignant potential of 5-8F, a highly metastatic NPC cell line, by restraining its growth, proliferation, mobility and migration. The present study demonstrated that PLCD3 may be an oncogenic protein in NPC and that it plays an important role in the progression of NPC partially by interacting with Flot2.

Tsao YT, Kuo CY, Kuan YD, et al.
The Extracts of
Int J Med Sci. 2017; 14(11):1049-1053 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Melanin is a normal production protecting skin from environment-causing damage. Plants produce some agents in response to their environment. These agents could be applied in cosmetic production. Some Chinese herbals have immunomodulatory activities and modulate the symptoms of several diseases. Melanogenesis represents a complex group of conditions that are thought to be mediated through a complex network of regulatory processes. Previously, some studies found that the extracts of

Drago-García D, Espinal-Enríquez J, Hernández-Lemus E
Network analysis of EMT and MET micro-RNA regulation in breast cancer.
Sci Rep. 2017; 7(1):13534 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Over the last years, microRNAs (miRs) have shown to be crucial for breast tumour establishment and progression. To understand the influence that miRs have over transcriptional regulation in breast cancer, we constructed mutual information networks from 86 TCGA matched breast invasive carcinoma and control tissue RNA-Seq and miRNA-Seq sequencing data. We show that miRs are determinant for tumour and control data network structure. In tumour data network, miR-200, miR-199 and neighbour miRs seem to cooperate on the regulation of the acquisition of epithelial and mesenchymal traits by the biological processes: Epithelial-Mesenchymal Transition (EMT) and Mesenchymal to Epithelial Transition (MET). Despite structural differences between tumour and control networks, we found a conserved set of associations between miR-200 family members and genes such as VIM, ZEB-1/2 and TWIST-1/2. Further, a large number of miRs observed in tumour network mapped to a specific chromosomal location in DLK1-DIO3 (Chr14q32); some of those miRs have also been associated with EMT and MET regulation. Pathways related to EMT and TGF-beta reinforce the relevance of miR-200, miR-199 and DLK1-DIO3 cluster in breast cancer. With this approach, we stress that miR inclusion in gene regulatory network construction improves our understanding of the regulatory mechanisms underlying breast cancer biology.

Gong X, Huang M
Long non-coding RNA MEG3 promotes the proliferation of glioma cells through targeting Wnt/β-catenin signal pathway.
Cancer Gene Ther. 2017; 24(9):381-385 [PubMed] Related Publications
Glioma has been identified as one of the most aggressive primary tumors. Long non-coding RNAs (lncRNAs), with length larger than 200 bp, have drawn increasing attention to their abnormal expression and regulation function in carcinogenesis. However, the role of lncRNAs in glioma remains largely unknown. Maternally expressed gene 3 (MEG3), also known as gene-trap locus 2 (GTL2), is an imprinted gene, and is encoded by the MEG3 transcript of the DLK1/MEG3 locus on human chromosome, or Meg3 on mouse chromosome. In this study, we found that lncRNA MEG3 was significantly downregulated in malignant glioma tissues and cell lines. The employment of the loss-of and gain-of functions assays presented that MEG3 suppressed glioma cells proliferation and induced cell-cycle arrest. Furthermore, our findings showed that highly expressed MEG3 could weaken Wnt/β-catenin signaling in glioma. Collectively, our findings revealed that downregulated lncRNA MEG3 could promote glioma cell proliferation through targeting Wnt/β-catenin signaling, which mainly influenced cell cycle.

Slemmons KK, Crose LES, Riedel S, et al.
A Novel Notch-YAP Circuit Drives Stemness and Tumorigenesis in Embryonal Rhabdomyosarcoma.
Mol Cancer Res. 2017; 15(12):1777-1791 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Rhabdomyosarcoma (RMS), a cancer characterized by skeletal muscle features, is the most common soft-tissue sarcoma of childhood. While low- and intermediate-risk groups have seen improved outcomes, high-risk patients still face a 5-year survival rate of <30%, a statistic that has not changed in over 40 years. Understanding the biologic underpinnings of RMS is critical. The developmental pathways of Notch and YAP have been identified as potent but independent oncogenic signals that support the embryonal variant of RMS (eRMS). Here, the cross-talk between these pathways and the impact on eRMS tumorigenesis is reported. Using human eRMS cells grown as three-dimensional (3D) rhabdospheres, which enriches in stem cells, it was found that Notch signaling transcriptionally upregulates

Enterina JR, Enfield KSS, Anderson C, et al.
DLK1-DIO3 imprinted locus deregulation in development, respiratory disease, and cancer.
Expert Rev Respir Med. 2017; 11(9):749-761 [PubMed] Related Publications
INTRODUCTION: The imprinted DLK1-DIO3 locus at 14q32.1-32.31 holds biological significance in fetal development, whereby imprinting errors are causal to developmental disorders. Emerging evidence has implicated this locus in other diseases including cancer, highlighting the biological parallels between fetal organ and tumour development. Areas covered: Controlled regulation of gene expression from the imprinted DLK1-DIO3 locus at 14q32.1-32.31 is crucial for proper fetal development. Deregulation of locus gene expression due to imprinting errors has been mechanistically linked to the developmental disorders Kagami-Ogata Syndrome and Temple Syndrome. In adult tissues, deregulation of locus genes has been associated with multiple malignancies although the causal genetic mechanisms remain largely uncharacterised. Here, we summarize the genetic mechanisms underlying the developmental disorders that arise as a result of improper locus imprinting and the resulting developmental phenotypes, emphasizing both the coding and noncoding components of the locus. We further highlight biological parallels common to both fetal development and disease, with a specific focus on lung development, respiratory disease, and lung cancer. Expert commentary: Many commonalities between respiratory and developmental defects have emerged with respect to the 14q32 locus, emphasizing the importance of studying the effects of imprinting on gene regulation patterns at this locus in both biological settings.

Bettinsoli P, Ferrari-Toninelli G, Bonini SA, et al.
Notch ligand Delta-like 1 as a novel molecular target in childhood neuroblastoma.
BMC Cancer. 2017; 17(1):352 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
BACKGROUND: Neuroblastoma is the most common extracranial solid malignancy in childhood, responsible for 15% of all pediatric cancer deaths. It is an heterogeneous disease that does not always respond to classical therapy; so the identification of new and specific molecular targets to improve existing therapy is needed. We have previously demonstrated the involvement of the Notch pathway in the onset and progression of neuroblastoma. In this study we further investigated the role of Notch signaling and identified Delta-like 1 (DLL1) as a novel molecular target in neuroblastoma cells with a high degree of MYCN amplification, which is a major oncogenic driver in neuroblastoma. The possibility to act on DLL1 expression levels by using microRNAs (miRNAs) was assessed.
METHODS: DLL1 mRNA and protein expression levels were measured in three different neuroblastoma cell lines using quantitative real-time PCR and Western Blot analysis, respectively. Activation of the Notch pathway as a result of increased levels of DLL1 was analyzed by Immunofluorescence and Western Blot methods. In silico tools revealed the possibility to act on DLL1 expression levels with miRNAs, in particular with the miRNA-34 family. Neuroblastoma cells were transfected with miRNA-34 family members, and the effect of miRNAs transfection on DLL1 mRNA expression levels, on cell differentiation, proliferation and apoptosis was measured.
RESULTS: In this study, the DLL1 ligand was identified as the Notch pathway component highly expressed in neuroblastoma cells with MYCN amplification. In silico analysis demonstrated that DLL1 is one of the targets of miRNA-34 family members that maps on chromosome regions that are frequently deregulated or deleted in neuroblastoma. We studied the possibility to use miRNAs to target DLL1. Among all miRNA-34 family members, miRNA-34b is able to significantly downregulate DLL1 mRNA expression levels, to arrest cell proliferation and to induce neuronal differentiation in malignant neuroblastoma cells.
CONCLUSIONS: Targeted therapies have emerged as new strategies for cancer treatment. This study identified the Notch ligand DLL1 as a novel and attractive molecular target in childhood neuroblastoma and its results could help to devise a targeted therapy using miRNAs.

Seo Y, Kim YS, Lee KE, et al.
Anti-cancer stemness and anti-invasive activity of bitter taste receptors, TAS2R8 and TAS2R10, in human neuroblastoma cells.
PLoS One. 2017; 12(5):e0176851 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Neuroblastoma (NB) originates from immature neuronal cells and currently has a poor clinical outcome. NB cells possess cancer stem cells (CSCs) characteristics that facilitate the initiation of a tumor, as well as its metastasis. Human bitter taste receptors, referred to as TAS2Rs, are one of five types of basic taste receptors and they belong to a family of G-protein coupled receptors. The recent finding that taste receptors are expressed in non-gustatory tissues suggest that they mediate additional functions distinct from taste perception. While it is generally admitted that the recognition of bitter tastes may be associated with a self-defense system to prevent the ingestion of poisonous food compounds, this recognition may also serve as a disease-related function in the human body. In particular, the anti-cancer stemness and invasion effects of TAS2Rs on NB cells remain poorly understood. In the present study, endogenous expression of TAS2R8 and TAS2R10 in SK-N-BE(2)C and SH-SY5Y cells was examined. In addition, higher levels of TAS2R8 and TAS2R10 expression were investigated in more differentiated SY5Y cells. Both TAS2Rs were up-regulated following the induction of neuronal cell differentiation by retinoic acid. In addition, ectopic transfection of the two TAS2Rs induced neurite elongation in the BE(2)C cells, and down-regulated CSCs markers (including DLK1, CD133, Notch1, and Sox2), and suppressed self-renewal characteristics. In particular, TAS2RS inhibited tumorigenicity. Furthermore, when TAS2Rs was over-expressed, cell migration, cell invasion, and matrix metalloproteinases activity were inhibited. Expression levels of hypoxia-inducible factor-1α, a well-known regulator of tumor metastasis, as well as its downstream targets, vascular endothelial growth factor and glucose transporter-1, were also suppressed by TAS2Rs. Taken together, these novel findings suggest that TAS2Rs targets CSCs by suppressing cancer stemness characteristics and NB cell invasion, thereby highlighting the chemotherapeutic potential of bitter taste receptors.

Nueda ML, Naranjo AI, Baladrón V, Laborda J
Different expression levels of DLK1 inversely modulate the oncogenic potential of human MDA-MB-231 breast cancer cells through inhibition of NOTCH1 signaling.
FASEB J. 2017; 31(8):3484-3496 [PubMed] Related Publications
NOTCH receptors participate in cancer cell proliferation and survival. Accumulated evidence indicates that, depending on the cellular context, these receptors can function as oncogenes or as tumor-suppressor genes. The epidermal growth factor-like protein delta-like homolog (DLK)1 acts as a NOTCH inhibitor and is involved in the regulation of normal and tumoral growth. In this work, we focused on the role of DLK1 in the control of breast cancer cell growth, a tumor type in which NOTCH receptors have been shown to play both opposite roles. We found that human DLK1 inhibits NOTCH signaling in MDA-MB-231 breast cancer cells. The proliferation rate and invasion capabilities of these cells depended on the level of NOTCH activation and signaling, as regulated by DLK1. High levels of DLK1 expression led to a significant decrease in NOTCH signaling, which was associated with a decrease in breast cancer cell proliferation and invasion. On the contrary, lower levels of NOTCH inhibition, caused by lower levels of DLK1 overexpression, led to enhanced

Day FR, Thompson DJ, Helgason H, et al.
Genomic analyses identify hundreds of variants associated with age at menarche and support a role for puberty timing in cancer risk.
Nat Genet. 2017; 49(6):834-841 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
The timing of puberty is a highly polygenic childhood trait that is epidemiologically associated with various adult diseases. Using 1000 Genomes Project-imputed genotype data in up to ∼370,000 women, we identify 389 independent signals (P < 5 × 10

Shao Q, Luo X, Yang D, et al.
Phospholipase Cδ1 suppresses cell migration and invasion of breast cancer cells by modulating KIF3A-mediated ERK1/2/β- catenin/MMP7 signalling.
Oncotarget. 2017; 8(17):29056-29066 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Phospholipase C δ1 (PLCD1) encodes an enzyme involved in energy metabolism, calcium homeostasis and intracellular movement. It is located at 3p22 in a region that is frequently deleted in multiple cancers, and the PLCD1 enzyme is a potential tumour suppressor in breast cancer that inhibits matrix metalloprotease (MMP) 7, but the detailed mechanism remains elusive. In this study, we found that PLCD1 was downregulated in breast cancers, and the gain-or-loss functional assay revealed that PLCD1 inhibited cell migration and invasion in vitro via the ERK1/2/β-catenin/MMP7 signalling pathway. Furthermore, KIF3A was identified as a downstream mediator of PLCD1, and there was an inverse correlation between the expression of PLCD1 and KIF3A. Knockdown of KIF3A expression alone suppressed cell migration and invasion, and attenuated ERK1/2/β-catenin/MMP7 signalling that was reactivated by knocking down PLCD1 in vitro. Collectively, our findings suggest that PLCD1 acts as a tumour suppressor, by KIF3A-mediated suppression of ERK1/2/β-catenin/MMP7 signalling, at least in part, in breast cancer.

Ding J, Kuo ML, Su L, et al.
Human mitochondrial pyrroline-5-carboxylate reductase 1 promotes invasiveness and impacts survival in breast cancers.
Carcinogenesis. 2017; 38(5):519-531 [PubMed] Related Publications
Human mitochondrial pyrroline-5-carboxylate reductase (PYCR) is a house-keeping enzyme that catalyzes the reduction of Δ1-pyrroline-5-carboxylate to proline. This enzymatic cycle plays pivotal roles in amino acid metabolism, intracellular redox potential and mitochondrial integrity. Here, we hypothesize that PYCR1 might be a novel prognostic biomarker and therapeutic target for breast cancer. In this study, breast cancer tissue samples were obtained from Zhejiang University (ZJU set). Immunohistochemistry analysis was performed to detect the protein level of PYCR1, and Kaplan-Meier and Cox proportional analyses were employed in this outcome study. The prognostic significance and performance of PYCR1 mRNA were validated on 13 worldwide independent microarray data sets, composed of 2500 assessable breast cancer cases. Our findings revealed that both PYCR1 mRNA and protein expression were significantly associated with tumor size, grade and invasive molecular subtypes of breast cancers. Independent and pooled analyses verified that higher PYCR1 mRNA levels were significantly associated with poor survival of breast cancer patients, regardless of estrogen receptor (ER) status. For in vitro studies, inhibition of PYCR1 by small-hairpin RNA significantly reduced the growth and invasion capabilities of the cells, while enhancing the cytotoxicity of doxorubicin in breast cancer cell lines MCF-7 (ER positive) and MDA-MB-231 (ER negative). Further population study also validated that chemotherapy significantly improved survival in early-stage breast cancer patients with low PYCR1 expression levels. Therefore, PYCR1 might serve as a prognostic biomaker for either ER-positive or ER-negative breast cancer subtypes and can also be a potential target for breast cancer therapy.

Pu Y, Zhao F, Wang H, Cai S
MiR-34a-5p promotes multi-chemoresistance of osteosarcoma through down-regulation of the DLL1 gene.
Sci Rep. 2017; 7:44218 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
MiR-34a-5p has been implicated in the tumorigenesis and progression of several types of cancer. However, the role of miR-34a-5p in osteosarcoma (OS) remains largely unknown. This study was performed in two multi-chemosensitive (G-292 and MG63.2) and two resistant (SJSA-1 and MNNG/HOS) OS cell lines. MiR-34a-5p promotes OS multi-chemoresistance via its repression of the Delta-like ligand 1 (DLL1) gene, the ligand of the Notch pathway, and thus negatively correlates with OS chemoresistance. The siRNA-mediated repression of the DLL1 gene suppressed cell apoptosis and de-sensitized G-292 and MG63.2 cells, while overexpression of DLL1 sensitized SJSA-1 and MNNG/HOS cells to drug-induced cell death. In agreement with the changes in the drug-induced cell death, the activity of the ATF2/ATF3/ATF4 signaling pathway was significantly altered by a forced reversal of miR-34a-5p or DLL1 levels in OS cells. DLL1 is a target of miR-34a-5p and negatively regulates the multi-chemoresistance of OS. This study suggested that miR-34a-5p, DLL1 and the ATF2/ATF3/ATF4 signaling pathway-associated genes are the potential diagnostic and/or therapeutic targets for an effective chemotherapy of OS. Our results also provide novel insights into the effective chemotherapy for OS patients.

Shui Y, Yu X, Duan R, et al.
miR-130b-3p inhibits cell invasion and migration by targeting the Notch ligand Delta-like 1 in breast carcinoma.
Gene. 2017; 609:80-87 [PubMed] Related Publications
Breast carcinoma is the most common malignancy in women, and the incidence rate has increased dramatically in recent years. Metastasis is responsible for most advanced breast cancer mortality, but the underlying mechanisms remain poorly understood despite extensive research. Recently, short non-coding RNA molecules, including miRNAs, which mediate changes in signalling pathways, have emerged as metastatic regulators of the breast carcinoma. Previous reports have suggested that miR-130b-3p has both oncogenic and tumour suppressor functions in a cancer type-dependent manner. However, the roles and underlying molecular mechanisms of miR-130b-3p in the development of metastasis in breast carcinoma remain unclear. Here, we reported for the first time that miR-130b-3p was differentially expressed in early-stage non-invasive MCF-7 human breast carcinoma cells and aggressive late-stage MDA-MB-231 cells. In gain-of-function and loss-of-function studies, we demonstrated that miR-130b-3p could inhibit breast carcinoma cell invasion and migration by directly targeting the Notch ligand Delta-like 1 (DLL1). Our data also indicated that MMP-9, MMP-13, and VEGF were regulated by miR-130b-3p and may be involved in the inhibition of cell invasion and migration in breast carcinoma. Collectively, our findings reveal a new regulatory mechanism of miR-130b-3p and suggest that miR-130b-3p may be a potential target against human breast cancer metastasis.

Nagy Z, Szabó PM, Grolmusz VK, et al.
MEN1 and microRNAs: The link between sporadic pituitary, parathyroid and adrenocortical tumors?
Med Hypotheses. 2017; 99:40-44 [PubMed] Related Publications
Sporadic tumors of the pituitary, parathyroids and adrenal cortex are unique, as their benign forms are very common, but malignant forms are exceptionally rare. Hereditary forms of these tumors occur in multiple endocrine neoplasia syndrome type 1 (MEN1). We hypothesize that the pathogenic link among the sporadic tumors of these organs of different germ layers might be represented by common molecular pathways involving the MEN1 gene and microRNAs (miR). miR-24 might be a microRNA linking the three tumor entities, but other candidates such as miR-142-3p and microRNAs forming the DLK1-MEG3 miRNA cluster might also be of importance.

Chang C, Liu T, Huang Y, et al.
MicroRNA-134-3p is a novel potential inhibitor of human ovarian cancer stem cells by targeting RAB27A.
Gene. 2017; 605:99-107 [PubMed] Related Publications
The cluster of microRNAs (miRNAs) in the DLK1-DIO3 genomic imprinted region contains several miRNAs that have a significant regulatory role in tumor proliferation and invasion. One of these miRNAs is miR-134-3p, and its expression changes significantly in human ovarian cancer stem cells (OCSCs) and in CD44-/CD133- ovarian cancer. The results of a luciferase assay showed that miR-134-3p silenced RAB27A by binding to the 3'-UTR of RAB27A mRNA. Overexpression of miR-134-3p in human OCSCs can not only inhibit the expression of RAB27A but also can effectively downregulate the expression of some tumor proliferation and invasion genes. Overexpression of miR-134-3p can not only inhibit the in vitro proliferation and cell cycle progression of human OCSCs but also can decrease the tumorigenicity in nude mice.

Makoukji J, Makhoul NJ, Khalil M, et al.
Gene expression profiling of breast cancer in Lebanese women.
Sci Rep. 2016; 6:36639 [PubMed] Article available free on PMC after 23/11/2019 Related Publications
Breast cancer is commonest cancer in women worldwide. Elucidation of underlying biology and molecular pathways is necessary for improving therapeutic options and clinical outcomes. Molecular alterations in breast cancer are complex and involve cross-talk between multiple signaling pathways. The aim of this study is to extract a unique mRNA fingerprint of breast cancer in Lebanese women using microarray technologies. Gene-expression profiles of 94 fresh breast tissue samples (84 cancerous/10 non-tumor adjacent samples) were analyzed using GeneChip Human Genome U133 Plus 2.0 arrays. Quantitative real-time PCR was employed to validate candidate genes. Differentially expressed genes between breast cancer and non-tumor tissues were screened. Significant differences in gene expression were established for COL11A1/COL10A1/MMP1/COL6A6/DLK1/S100P/CXCL11/SOX11/LEP/ADIPOQ/OXTR/FOSL1/ACSBG1 and C21orf37. Pathways/diseases representing these genes were retrieved and linked using PANTHER

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